Electrode for electrolytic devices



Feb. 18, 1941. c. SHUGG ETAL ELECTRODE FOR ELECTROLYTIC DEVICES 3 Sheets-Sheet 1 Filed June 24, 1937 mvsmoxs CARLETON WUGG W4AX1YN4B 49 .543 W m7 ATZRNEYS c. SHUGG ETAL 84 ELECTRODE FOR ELECTROLYTIC DEVICES Feb. 18, 1941.

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ELECTRODE FOR ELECTROLYTIC DU IICES Filed June '24, 19s? 3 Shoets'Sheet 3 IN VENTORS CARLETON SHUGG LQMAXKNAB 6 7, && fia/zmw ATTORNEYS Patented Feb. 18, 1941 UNITED STATES ELECTRODE ron ELECTROLYTIC DEVICES Carleton Shun. Stamford, Vt., and Max Knab, Brooklyn, N. Y., assignors to Sprague Specialties Company, North Adams, Mass a corporation of Massachusetts Application June 24,

Claims.

The present invention relates to electrolytic.

devices such as electrolytic condensers, rectifiers and the like having film-forming electrodes, and more particularly to a novel electrode construction for such electrolytic devices and the process of making the same.

We shall describe our invention in connection with electrolytio'condensers for which it is of particular utility; however, it should be well understood that'it is not limited to such.

Electrolytic condensers, as it is well known, comprise one or more electrodes of a metal exhibiting film-forming properties, for example of aluminum, and which are provided with a film which forms the dielectric of the condenser.

As the capacity of an electrolytic condenser is proportional to the area of the filmed electrode (anode), to obtain a high capacity in a small volume, it is desirable to have a compact anode 0 with as large a surface area as possible.

The object of our invention is to provide a novel electrode construction having a very large effective surface area for a given volume.

Another object of our invention is to provide 85 for an electrode which is easy to manufacture and assemble, and which while being of very thin material and thus very light, has so great inherent rigidity as to maintain its shape without requiring separate supports.

80 According to the invention, the above enumerated advantages are obtained by forming the electrode of a" flat strip of foil iolded into a U or V shape and subsequently winding the foil into a helix.

We are aware that it has been proposed to shape electrodesas flat helices, but past endeavors in using such electrodes have not been successful. This because. if thin material was used the construction had insuilicient rigidity,

whereas with thick material the construction became too expensive. The present invention obviates these drawbacks.

1In the drawings forming part of the specificat on:

4,5 Figure l is a cross-sectional elevation of an electrolytic condenser embodying'the invention;

Fig. 2 is a fractional, enlarged cross-sectional view of an electrolytic condenser showing a some what modified embodiment of the invention;-

Flg. 8 is an enlarged cross-sectional view of a portion 01 an electrode made in accordance with the invention;

Fig. 4 is a perspective view 01' a foil adapted to be formed into a helical electrode provided with an integral anode riser;

1937, Serial No. 150,170

Fig. 5 is a front elevation of the apparatus for helically forming the electrode;

Fig. 6 is a top plan view of the apparatus of Fig, 5; 2

Fig. 7 is a side elevation of a portion of the apparatus of Fig. 5;

Fig. 8 is a front elevation of the fixture to fold the foil;

Fig. 9 is a bottom plan view of the fixture of Fig. 8;

Fig. 10 is a side view oi the fixture of Fig. 9. Referring to the drawings, the condenser shown in Fig. 1 comprises a metal container i, preferably of cylindrical shape. .and consisting of a suitable filming or non-filming metal, and which constitutes the cathode of the condenser. The

container i has an enlarged neck portion shown at l which may be threaded for mounting the condenser on a suitable base.

The anode 3 consists of a ribbon of suitable filming metal, for example aluminum, magnesium, etc., shaped in accordance with the invention, being a double helix having a U or V shaped cross-section.

The anode I is secured to a riser I at a single point I, the inherent rigidity of structure making it unnecessary to support the full at both ends. The riser may be of filming metal, as aluminum, or may be of an insulating material, resistant to the electrolyte, such as rubber or "Bakelite."

Disposed within the neck 4 is a plug 8' of soft rubber or similar resilient gasket-material, which is provided with a bore 8 through which snugly passes the end of anode riser 1. Proper air and liquid-tight sealing can be obtained by fiuting "the neck portion II of the container 1, as described in Patent #l,996,982 to R. C. Sprague et al.

If the riser 1 is made of insulating material proper electrical connection of the anode can be obtained by extending part of the metal foil along with the anode riser through the plug 8.

The top of the container I is provided with a crimped metal cap i0 which fits into the container I at H. The. free edge oi the cap in together with a gasket i2 of wax-impregnated cloth or similar gasket material, is crimped over a rim provided on the free end of container i.

The electrolyte I! may be any electrolyte suitable for electrolytic condensers, for example a combination of a weak acid and a salt as borax and boric acid, and the viscosity of the electroly'te may vary within wide limits.

Intel-posed between the anode and the container is a spacer ll of rubber, Bakelite," Celluloid or other insulating material not attacked by the electrolyte. To insure free e of the electrolyte between the cathode-container and the anode, the insulator N is preferably provided with suitable perforations I5.

A suitable spacer construction in accordance with the invention is shown in Fig. 2. The spacer i8 is of insulating material cut in the form of a helix which is interleaved with the anode. The spacer it may have an outside diameter substantially equal to the inside diameter of the cathode container so as to snugly fit into the container. It is preferably provided with compare:

tively large and numerous perforations ii to provide for a satisfactory communication of the electrolyte between the anode portions.

The apparatus to make the electrodes of the invention is shown in Figs. 5 to 10. It comprises a supporting frame II which is rigidly mounted on a suitable base (not shown). Passing through the frame 25 and supported thereby are two spindle shafts 28 and 21, which carry suitably aiilxed driving gears 2! and 25 respectively. The driving gears and 2! are identical in size and shape and are adapted through their engagement to rotate the spindle shafts I! and 21 at equal and opposite speeds. In the arrangement shown shaft 26 is driven clockwise and shaft 2! is driven counterclockwise.

Thrust bearings 48 and serveto reduce friction losses between the gears 28 and 2' and the frame 25.

The driving power may be supplied in any suitable manner, and applied for example through 'a suitable pulley or gear (not shown), which is attached to the extension I! of the spindle shaft 21.

Mixed to the opposite ends of the spindle shafts and preferably formed as an integral part thereof, are forming rollers 22 and 23. These rollers are outwardly tapered. having thus their largest diameter at their end nearest to the frame 25.

7 Located within a slot tween the forming rollers 22 and 28 and suitably spaced therefrom, is a forming wheel 24; The

formingwheelflismountedonafreenmning shaft it carried in bearings IP-II' and is allowed free rotative motion therein.

The wheel 24 preferably has a large diameter as compared with the axial length of the rollers 22 and II, for example a ratio of about 5 being quite suitable. 1

The forming rollers 22 and 2! and forming wheel N are made of suitable hardened material. for example high-tempered steel.

Mounted on the frame II by suitable mounting means, for example bolts 33, and with its longitudinal axis perpendicular to the axis of the shaft ll oi the forming wheel, is a foilbendlngnxturell,shownindetailinl'igs.lto l0. 7 The 'ilxture 50 comprises two mounting brackets 82-42, a guide frame 84, a protruding arm foil guard 58, and a'siot 85 which converges from the substantially rectangular shape shown atits entrancefltothedesired UorVshape atitspointofelrelafl.

To form the helical electrode of the invention, a suitable metal foil. for example of aluminum, having awldthtwicethatofthercqllll'qd depth, of the helix. is threaded through the quasirectangular opening 10 of the guide structure 50 and pulled therethrwgh. The convergence of u the guide slot slimlin to m nu foil the de- I! of the frame 25, be-V sired folded shape so that at the point of egress II it will have a V or U cross section depending on the shape of the slot.

From 31 the foil is led into the space formed by the tapered rollers 22 and 25 and the forming wheel 24, where the rotating rollers take hold of it and cause it to advance and to be distorted.

This distortion of the foil because of the tapered shape of the rollers is not equal along the entire depth of the foil, but those portions which contact with the larger diameter portion of the rollers 22 and II will be caused to compress and elongate more and consequently to be distorted to a greater area than the foil portions I adjacent to the smaller diameter portions of the rollers. As a result the foil emerging from the 7 used The protruding arm 88 of the guide structure serves to prevent any displacement of the toil from between the rollers, during its contact with the rollers, whereas the forming wheel 24 serves to internally support the foil during this process. For example if high-purity -aluminum foil .75" wide and .014" thick is drawn through the guide slot Cl which imports to it a U shape at the point of egress II, the foil through its passage between rollers 2! and II which are .5" long and have maximum and minimum diameters of .683" and .667" respectively, will automatically wind itself into a helix having an outside diameter of 1.125." It is to be noted that the width of the gap between the forming wheel 24 and the smallest 1 diameter of the tapered rollers should equal the thickness of the foil. If the thickness of the foil is greater than this gap, unnecessarily high compression and distortion forces are required; whereas foils with a thickness less than that of the gap will not be compressed along the entire depth of the fold and therefore the helix will have a larger diameter than desired.

Various modifications of the invention may suggest themselves, for example the electrode support or riser may be formed as an integral part of the electrode. For such a construction a metal rod may be used which is flattened along that part of its length which is to form the effective portion of the electrode. The flattened portion ll ofsuchgrodasshownini'igurei,

'isthenfoldedinto'auorvshopeandwound into a helix by the method of the invention, whereastheremainingportionilsarvesasthe electrode riser and terminal connection.

While we have described our invention with speciilc examples and in specific embodiments, it should be well understood that we do not wish to be limited thereto, but desire the appended 'claimstobeconstruedasbroadlyaspermissible comprising a iolded ribbon having a greater 4. An electrode for electrolytic devices com- 1 thickness at its fold than at its edges, said prising a flat double helical coil consisting of a. folded ribbon having the shape of a flat double folded ribbon of filming metal, the radial width helical coil the radial width of the folded ribbon of the folded ribbon being not less than, one- 51 being not less than one-third the outside diamthird the outside diameter of the helical coil, 4 eteroi the helical coil. 5. An electrode for electrolytic devices com- 3. An electrode for electrolytic condensers prising a flat double helical coil of a filming comprising a folded ribbon of film-forming metal ribbon, the individual turns of said libbon metal, said ribbon having a thickness uniformly having a. substantially U-shaped cross-section, i0 increasing from the edges towards the fold, said the radial width of said ribbon being not less 10 folded ribbon forming a flat double helical-coil than one-third the outside diameter of the helithe radial width of the folded ribbon being not cal coil. 7

less than one-third the outside diameter of the CARLETON SHUGG.

helical coil. MAX KNAB. 

